"This gung-ho approach to GMOs also has to be seen in the context of the EU-US TTIP negotiations and the long-running US campaign to force their GMOs on to the EU market," he said.

On Wednesday, the Commission proposed a new law allowing individual EU countries to restrict or ban imported GM crops, even if those crops have been authorised EU-wide by the European Food Safety Authority (Efsa).

A country would have to justify its opt-out from a certain GM crop type, stating specific national or regional grounds for the restriction.

Social or environmental impact could be cited as justification for a national ban, rather than purely health concerns.

US Trade Representative Michael Froman said the proposal left the US "very disappointed" and he called it "hard to reconcile with the EU's international obligations".

The only GM crop cultivated in the EU - Monsanto's maize variety MON 810 - is banned in several EU countries. Spain is by far the biggest grower of MON 810 in Europe, but the crop accounts for just 1.56% of the EU's total maize-growing area.

The UK government is among several countries, including Spain and Sweden, calling for the EU's GM rules to be eased.

However, there is strong opposition in many other countries, including in Austria, France and Germany.